Weapon detector with user interface

ABSTRACT

A detector for detecting the removal and/or insertion of a firearm out of and/or into a holster. The detector may transmit a message each time the firearm is removed from the holster. A recording system may receive the message and determine whether or not it will begin recording the data it captures. A detector may detect the change in a magnitude of an inductance and/or an impedance of a circuit to detect insertion and removal of the firearm into and out of the holster. The holster is configured to couple to the detector to position the detector to detect insertion and removal of the firearm. An adhesive tape may couple a detector to a holster.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/994,066, filed Aug. 14, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/218,086, filed Dec. 12, 2018, now issued as U.S.Pat. No. 10,775,131, which is a continuation of U.S. patent applicationSer. No. 15/842,149, filed Dec. 14, 2017, now issued as U.S. Pat. No.10,190,846, which claims the benefit of U.S. Provisional Application No.62/458,941, filed Feb. 14, 2017, each of which are incorporated byreference in their entirety.

FIELD OF THE INVENTION

Embodiments of the present invention relate to a detector that detects aweapon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Embodiments of the present invention will be described with reference tothe drawing, wherein like designations denote like elements, and:

FIG. 1 is a block diagram of a system for providing a notice accordingto various aspects of the present disclosure;

FIG. 2 is a diagram of an implementation of the coil of FIG. 1;

FIG. 3 is a cross-section view of the coil of FIG. 2 along 3-3;

FIG. 4 is a diagram of an electromagnetic field from the coil of FIG. 1or FIG. 2 in the absence of a weapon;

FIG. 5 is a diagram of the electromagnetic field from the coil of FIG. 1or FIG. 2 in the presence of a weapon;

FIG. 6 is a view of an implementation of the system for providing anotice of FIG. 1 with a first implementation for mounting the detectorproximate to the holster;

FIG. 7 is an exploded view of the implementation of the system forproviding a notice of FIG. 6;

FIG. 8 is an exploded view of the implementation of detector of FIGS. 6and 7;

FIG. 9 is a front view of the implementation of the detector of FIGS.6-8;

FIG. 10 is a view of an implementation of the system for providing anotice of FIG. 1 with a second implementation for mounting the detectorproximate to the holster;

FIG. 11 is an exploded view of the second implementation for mountingthe detector of FIG. 10;

FIG. 12 is a state diagram of the operating modes of the detectors ofFIGS. 1 and 6-11; and

FIG. 13 is a state diagram of a method for monitoring the presence orabsence of a firearm.

DETAILED DESCRIPTION OF THE INVENTION

Body cameras, vehicle cameras, wireless microphones and/or otherrecording systems are used by many security forces to record the eventsof an incident. Security forces include police departments,investigative and enforcement departments of a government (e.g., DOJ,FBI, CIA, ATF, CPB), and military forces. A recording, if properlyhandled, may serve as evidence in a subsequent proceeding. The operationof a recording system may be initiated manually or by a trigger. Atrigger may include a signal sent to the recording system. A signal maybe sent by a wired or wireless circuit. A signal sent wirelessly mayinclude sending a message (e.g., information, data packet) using anyconventional wireless communication protocol.

A trigger may be obligatory or permissive. A recording system (e.g.,recording device, camera, microphone, video recorder) must initiaterecording upon receipt of an obligatory trigger. A recording system thatreceives a permissive trigger is not required to initiate recording. Apermissive trigger may include a message transmitted and/or receivedwirelessly that reports the status and/or the identity of the devicesending the message. A recording system may initiate recording dependingon the value of the status. A recording system may initiate recordingdepending on the value identity of the sending device. A recordingsystem may decline to initiate recording from some values.

A situation for which it is desirable to initiate recording by recordingsystems is when a security officer draws a weapon (e.g., firearm). Inmany instances, personnel of security forces carry conventionalfirearms. In many instances, such firearms are carried bodily in aholster for transport and immediate access in case of need. Withdrawinga weapon from a holster may indicate that events of an incident areabout to occur or that have just occurred should be recorded. A systemfor providing a notice, as discussed herein, may detect withdrawal of aweapon from a holster and provide a notice (e.g., trigger, message,permissive trigger, obligatory trigger) that the weapon has beenwithdrawn. A notice system may provide a notice in the form of a messagetransmitted wirelessly. Recording systems may receive the wirelessnotice. A recording system, depending on the type of notice (e.g.,obligatory, permissive) may start recording.

A system for providing a notice may also provide a notice that theweapon has been inserted into the holster.

A system for providing a notice may provide a permissive trigger. Asystem for providing a notice may provide information that a recordingsystem may use to determine whether or not to start recording. Arecording system may use information provided by a system for providinga notice to perform other functions.

Information may include a unique identifier (e.g., alphanumerical,serial number) of a detector, a state of operation of the detector,and/or an identity of the user of the system that provides the notice.

For example, system for providing a notice system 100 of FIG. 1 includesdetector 110 and firearm system 140. Firearm system 140 includes firearm142 and holster 150. Firearm 142 may include a conventional handheldfirearm. Firearm 142 includes barrel 144. At least a portion of barrel144 is formed of metal that is susceptible to detection using inductivesensing.

Detector 110 includes processing circuit 112, memory 114, user interface116, communication circuit 122, real-time clock 124, authenticationcircuit 126, sensor circuit 128, and coil 130. User interface 116includes control 118 and indicator 120. Detector 110 may further includeNFC tag 860.

A detector detects whether a firearm is positioned in a holster. Adetector detects whether a firearm is positioned out of (e.g., removedfrom) the holster. Depending on the implementation of the sensorcircuit, the coil, and their sensitivity, a detector may detect theposition of a firearm in a holster as opposed to solely whether thefirearm is in or out of the holster.

A detector may wirelessly transmit a notice (e.g., message, data packet,data, signal, trigger) in response to detecting a change in the statusof a firearm with respect to a holster. A change in status includeswithdrawing of the firearm from the holster and inserting the firearminto the holster. The notice may include information to describe thedetector transmitting the data, the user of the detector, the user ofthe firearm, the date and time of detecting, date and time oftransmission of the notice, the status of the holster (e.g., firearmwithdrawn, firearm inserted, firearm partially withdrawn, firearmpartially inserted), previously transmitted dates and/or times, and/orpreviously transmitted status. The notice may further includeinformation for authenticating the detector to one or more recordingsystems.

One or more recording systems may receive a notice from notice system100. A recording system may use the information transmitted with thenotice to determine whether or not (e.g., permissive trigger) to performan operation (e.g., perform a function). An operation of a recordingsystem may include starting (e.g., initiating) recording.

A detector may store information in a memory (e.g., a log). Informationstored by a detector may include information related to the operationand/or status of the detector. Information stored by a detector may bestored as an entry in the log. Each entry in a log may include the dateand time of recording the entry. Information stored in a log may includedetecting withdraw of a weapon from a holster, detecting insertion of aweapon into a holster, activation (e.g., starting, operation of) a muteoperation of the recorder, resetting of the detector, setting of thetime of the circuit used to generate timestamps or to record actions inthe log, executing a software (e.g., firmware) upgrade, updates to usersettings, reverting to an earlier version of software, and/or detectinga system fault. The mute operation, discussed in more detail below,alters the information transmitted in one or more notices for a periodof time.

A detector may receive information (e.g., data) such as information toupgrade the software of the detector. A detector may receive informationfrom a user via a user interface. A detector may provide information toa user via the user interface.

A processing circuit includes any circuitry, component, and/orelectrical/electronic subsystem for performing a function. A processingcircuit may include circuitry that performs (e.g., executes) a storedprogram. A processing circuit may include a digital signal processor, amicrocontroller, a microprocessor, an application specific integratedcircuit, a programmable logic device, logic circuitry, state machines,MEMS devices, signal conditioning circuitry, communication circuitry, aconventional computer, a conventional radio, a network appliance, databusses, address busses, and/or a combination thereof in any quantitysuitable for performing a function and/or executing one or more storedprograms.

A processing circuit may further include conventional passive electroniccomponents (e.g., resistors, capacitors, inductors) and/or activeelectronic components (op amps, comparators, analog-to-digitalconverters, digital-to-analog converters, programmable logic). Aprocessing circuit may include conventional data buses, output ports,input ports, timers, memory, and arithmetic units.

A processing circuit may provide and/or receive electrical signalswhether digital and/or analog in form. A processing circuit may provideand/or receive digital information via a conventional bus using anyconventional protocol. A processing circuit may receive information,manipulate the received information, and provide the manipulatedinformation. A processing circuit may store information and retrievestored information. Information received, stored, and/or manipulated bythe processing circuit may be used to perform a function and/or toperform a stored program.

A processing circuit may have a low power state in which only a portionof its circuits operate or it performs only certain functions. Aprocessing circuit may be switched (e.g., awoken) from a low power stateto a higher power state in which more or all of its circuits operate orit performs additional certain functions or all of its functions.

A processing circuit may control the operation and/or function of othercircuits and/or components of a system. A processing circuit may receivestatus information regarding the operation of other components, performcalculations with respect to the status information, and providecommands (e.g., instructions) to one or more other components for thecomponent to start operation, continue operation, alter operation,suspend operation, or cease operation. Commands and/or status may becommunicated between a processing circuit and other circuits and/orcomponents via any type of bus including any type of conventionaldata/address bus. A processing circuit may instruct a circuit orcomponent to enter a low power state. A processing circuit may instructa circuit or component to exit a low power state.

A memory stores information. A memory provides previously storedinformation. A memory may provide previously stored informationresponsive to a request for information. A memory may store informationin any conventional format. A memory may store electronic digitalinformation. A memory may provide stored data as digital information.

A memory includes any semiconductor, magnetic, or optical technology(e.g., device, chip, system), or a combination thereof for storinginformation. A memory may receive information from a processing circuitfor storage. A processing circuit may provide a memory a request forpreviously stored information. Responsive to the request the memory mayprovide stored information to the processing circuit.

A memory may include any circuitry for storing program instructionsand/or data. Storage may be organized in any conventional manner (e.g.,program code, buffer, circular buffer, database). Memory may beincorporated in and/or accessible by a transmitter, a receiver, atransceiver, a sensor, a controller, and/or a processing circuit.

A communication circuit transmits and/or receives information (e.g.,data). A communication circuit may transmit and/or receive (e.g.,communicate) information via a wired and/or wireless communication link.A communication circuit may communicate using wireless (e.g., radio,light, sound, vibrations) and/or wired (e.g., electrical, optical)mediums. A communication circuit may communicate using any wireless(e.g., Bluetooth, Zigbee, WAP, WiFi, NFC, IrDA, LTE, BLE, EDGE, EV-DO)and/or wired (e.g., USB, RS-232, Firewire, Ethernet) communicationprotocols.

A communication circuit may receive information from a processingcircuit for transmission. A communication circuit may provide receivedinformation to a processing circuit.

A communication circuit in one device (e.g., detector) may communicatewith a communication circuit in another device (e.g., smart phone,tablet, mobile computer, server). Communications between two devices maypermit the two devices to cooperate in performing a function of eitherdevice. For example, a user interface for a detector may be implementedon a smart phone that includes a touch screen. User interaction with theuser interface on the smart phone is communicated to the detector viathe communication circuits of the smart phone and detector. The detectorperforms the function indicated by the message from the smart phone. Anyinformation produced by the detector for the user may be communicatedfrom the detector to the smart phone via the communication circuits forpresentation on the display of the smart phone.

A user interface enables a human user to interact with an electronicdevice (e.g., detector). A user may control, at least in part, anelectronic device via the user interface. A user may provide informationand/or commands to an electronic device via a user interface. A user mayreceive information (e.g., status) and/or responses from the electronicdevice via the user interface.

A user interface may include one or more controls that permit a user tointeract and/or communicate with (e.g., provide information to) anelectronic device to control (e.g., influence) the operation (e.g.,functions) of the electronic device.

As discussed above, a user interface may provide information to a user.A user may receive visual, haptic (e.g., tactile, kinesthetic), and/oraudible information from a user interface. A user may receive visualinformation via devices (e.g., indicators) that visually displayinformation (e.g., LCDs, LEDs, light sources, graphical and/or textualdisplay, display, monitor, touchscreen). A user may receive audibleinformation via devices that provide an audible sound (e.g., speaker,buzzer). A user may receive tactile information via devices thatvibrate, move, and/or change resistance against a user's finger as it ispressed.

A user interface may include a communication circuit for transmittinginformation to an electronic device for presentation to a user, asdiscussed above.

A control includes any electromechanical device suitable for manualmanipulation by a user. A control includes any electromechanical devicefor operation by a user to establish or break an electrical circuit. Acontrol may include a portion of a touch screen. Operation of a controlmay occur by the selection of a portion of a touch screen. A control mayinclude a switch. A switch includes a pushbutton switch, a rockerswitch, a key switch, a detect switch, a rotary switch, a slide switch,a snap action switch, a tactile switch, a thumbwheel switch, a pushwheel switch, a toggle switch, a reed switch, and a key lock switch(e.g., switch lock).

A control may be operated in different manners by a user to providedifferent information to a detector. For example, in an implementationin which the control is implemented as a push button, a user may pressand release the button; press, hold the button for a period of time,then release the button during which the period of time for which thebutton is held determines whether the press is a long press or a verylong press; press the button, release, press again, release (e.g.,double press).

The term “control”, in the singular, represents a singleelectromechanical device for operation by a user to provide informationto a device. The term “controls”, in plural, represents a plurality ofelectromechanical devices for operation by a user to provide informationto a device. The term “controls” include at least a first control and asecond control.

A processing circuit may detect the operation of a control. A processingcircuit may perform a function responsive to operation of a control.Responsive to a control, a processor may perform a function, halt afunction, resume a function, or suspend a function of the electronicdevice of which the control and the processor are a part. A control mayprovide analog or binary information to a processor.

The function performed by an electronic device responsive to operationof a control may depend on the current operating state (e.g., presentstate of operation, present function being performed) of the electronicdevice of which the control is a part.

A user may receive information from an electronic device via anindicator. An indicator may provide information visually, via hapticfeedback, and/or audibly as discussed above. In an implementation inwhich the indicator is implemented as an LED, the indicator may conveyinformation by turning the LED on and off (e.g., blink) or vice versa,the color of light provided by the LED, the rate of turning the LED onand off, the duration of time the LED is on or off, and/or the sequenceof colors provided by the LED.

A real-time clock tracks (e.g., follows, keeps track of) the current(e.g., present) time. The functions of a real-time clock may beperformed by a processing circuit. A dedicated circuit may perform thefunctions of a real-time clock. A real-time clock may be highly accurate(e.g., 5 seconds-12 minutes lost or gained per year). A real-time clockmay further track day, date, and year. A real-time clock may provide thepresent time to a processing circuit. A real-time clock may track timeeven when other circuits are powered down. A processing circuit mayperform some or all of the functions performed by a real-time clock.

Authentication is the act of verifying a claim of identity.Authentication may be used to confirm a user's identity. For example, abank may authenticate the identity of a person requesting a withdrawalby asking for and inspecting photo ID. Computers may confirm theidentity of a user by the user providing a user name and password. Oneelectronic device may be authenticated to another electronic device.Authentication may also be accomplished by a challenge-response protocolin which one party, or electronic device, issues a challenge and theperson, or electronic device, must provide a valid answer to beauthenticated.

Cryptographic techniques may be used to confirm the identity of a user.For example, Public Key Infrastructure permits authentication usingpublic and private keys. One device has a private key and issues apublic key. When the device requests communication with another device,such as a computer, the computer generates and sends a random number tothe user. The user encrypts the random number using its private key. Thedevice sends the encrypted number back to the computer. The computeruses the device's public key to decrypt the encrypted number. If thedecrypted number matches the originally sent random number, then theidentity of the user has been authenticated to the computer.

An authentication circuit may be used to authenticate a user and/or anelectronic device. An authentication circuit may store keys, generaterandom numbers, generate guaranteed unique numbers, encrypt, anddecrypt. An authentication circuit may perform public key (e.g., PKI)algorithms such as high-speed PKI algorithms and elliptical curvealgorithms (e.g., P256, B283, K283). An authentication circuit mayperform digital signature algorithms such as Digital Signature Algorithm(e.g., FIPS 186, 186-1, 186-2, 186-3, 186-4) and elliptical curvedigital signature algorithms (e.g., FIPA 186-3).

An authentication circuit may cooperate with a processing circuit, auser interface, and/or a communication circuit to authenticate a userand/or a device.

A sensor circuit detects (e.g., measures, witnesses, discovers,determines) a physical property (e.g., intensive, extensive, isotropic,anisotropic). A physical property may include momentum, capacitance,electric charge, electric impedance, electric reactance, inductance,electric potential (e.g., electromotive force), frequency, luminance,luminescence, magnetic field, magnetic flux, mass, electromagneticfield, pressure, spin, stiffness, temperature, tension, velocity, sound,heat, and time. A sensor circuit may detect a quantity, a magnitude,and/or a change in a physical property. A sensor circuit may detect aphysical property and/or a change in a physical property directly and/orindirectly. A sensor circuit may detect a physical property and/or achange in a physical property of an object.

A sensor circuit may detect a physical quantity (e.g., extensive,intensive). A physical quantity may be positive, negative, or zero. Asensor circuit may detect a change in a physical quantity directlyand/or indirectly. A sensor circuit may detect one or more physicalproperties and/or physical quantities at the same time (e.g., inparallel), at least partially at the same time, or serially. A sensorcircuit may deduce (e.g., infer, determine, calculate) informationrelated to a physical property. A physical quantity may a magnitude ofany of the physical properties discussed above. For example, a physicalquantity may include an amount of time, an elapse of time, a magnitudeof an electric current, an amount of electrical charge, a magnitude of acurrent density, a magnitude of a voltage, an amount of capacitance, anamount of inductance, a magnitude of impedance, a magnitude ofreactance, a magnitude of a magnetic field, and a flux density.

A sensor circuit may provide force to detect a physical property and/ora physical quantity. A force may include an electromotive force (e.g.,voltage, current). A force may be provided before, coincident with,and/or after detecting. A force may be provided once, periodically,repeatedly, and/or as needed. An electromotive force may include adirect current (“DC”) or an alternating current (“AC”). For example, asensor circuit may provide a voltage to detect a capacitance. A sensorcircuit may provide a current to generate an electromagnetic fieldand/or to detect a change in an electromagnetic field. A sensor circuitmay provide a current to an LC circuit (e.g., LC tank circuit) to causethe LC circuit to oscillate. Providing a force may include providing acurrent to a coil to produce an electromagnetic field.

A sensor circuit may include and/or cooperate with a processing circuitfor detecting, transforming, relating, and deducing physical propertiesand/or physical quantities. A processing circuit that is part of orcooperates with a sensor circuit may include any conventional circuitfor detecting, transforming, relating, and deducing physical propertiesand/or physical quantities. For example, a processing circuit mayinclude a voltage sensor, a current sensor, a charge sensor, anelectromagnetic sensor, and/or a frequency sensor.

A sensor circuit may provide information. A sensor circuit may provideinformation regarding a physical property and/or a change in a physicalproperty. A sensor circuit may provide information regarding a physicalquantity and/or a change in a physical quantity. A sensor circuit mayprovide information regarding information determined using a processingcircuit.

For example, a sensor may drive an LC circuit, a frequency counter maymeasure the frequency of the oscillation of the LC circuit, the measuredfrequency may be compared to a reference frequency (e.g., clock), thecurrent drawn by the LC circuit may be measured and from the measuredfrequency and current the parallel resistance of the LC circuit may bededuced. The magnitude of the parallel resistance may be used todetermine whether the LC circuit operates in the presence or absence ofa weapon in a holster.

In another example, a sensor may be implemented using aninductance-to-digital converter (“LDC”), such as the LDC1101 from TexasInstruments. An LDC performs the functions of a sensor circuit. The LDCcouples to a coil, provides an alternating current to the coil togenerate an electromagnetic field through the coil, measures theinductance and/or equivalent parallel impedance of the circuit thatincludes the coil, converts the measure inductance and/or impedance to adigital number and reports the number. The LDC may also detect a changein the measured inductance and/or impedance. A processing circuit mayreceive the digital numbers reported by an LDC. An LDC may provide acurrent to an LC tank circuit, measure the frequency of the oscillationsof the LC tank circuit, and deduce the inductance of the LC tankcircuit, and report the inductance of the LC tank circuit.

An LDC may provide current to an LC tank circuit, measure the electricalcurrent or power consumed by the LC tank circuit, and deduce theelectrical resistance or impedance of the LC tank circuit, and reportthe resistance or impedance of the LC tank circuit.

Because metal (e.g., barrel of a gun) alters (e.g., changes, interactswith) with the electromagnetic field generated by the LDC via the coil,the LDC, in cooperation with processing circuit 112, may detect thepresence and/or absence of metal. The LDC may measure the inductance ofthe circuit that includes the coil in the absence of metal, measure theinductance in the presence of metal, and report the values to processingcircuit 112. Information from a user via user interface 116 may includewhether the firearm was in the holster or not for each measurement madeby the LDC.

Further, because metal (e.g., barrel of a gun) alters the value of theinductance in an LC tank circuit and thereby the resonant frequency ofthe LC tank circuit, an LDC coupled to the LC tank circuit may detectthe presence and/or absence of metal.

The LDC may measure the resonant frequency of an LC tank circuit thatincludes the coil in the absence of metal and the presence of metal andreports the values to processing circuit 112. Processing circuit 112 mayreceive information from the user via user interface 116 to associatethe information provided by the LDC with whether the gun was in theholster or not. Processing circuit 112 may determine whether the gun isin the holster using prior values reported by the LDC and the currentvalues reported by the sensor circuit 128.

A coil is a conductor shaped to form a closed geometric path. A closedgeometric path is not a closed conducting path unless the two ends ofthe coil are electrically coupled together. Coils may have multipleturns. A coil may be wrapped around an iron core or an insulating form,or it may be self-supporting. A coil may be formed in a plane of aprinted circuit board. A coil may be formed in one or more planes (e.g.,layers) of a printed circuit board.

Providing an AC signal to a coil causes the coil to generate anelectromagnetic field. Metal may interact (e.g., interfere) with theelectromagnetic field generated by a coil, as discussed above.Interaction of the magnetic field of a coil with metal alters themeasured inductance of the coil. A sensor circuit may provide an ACsignal to a coil to cause the coil to generate an electromagnetic field.A sensor circuit may detect the interaction of metal with theelectromagnetic field. A sensor circuit and coil may detect a proximityof metal by detecting the presence or absence of interaction with theelectromagnetic field by metal. Detecting interaction with theelectromagnetic field may be referred to as inductive sensing.

For example, coil 200 is formed of conductor 220 on one or more layersof printed circuit board (“PCB”) 210. The two end portions of conductor220, end portion 250 and end portion 350 are available to couple to asensor circuit. A forward portion of coil 200, the portion facingoutward in FIG. 2 and upward in FIG. 3, is for positioning toward aholster for detecting the presence or absence of the metal of a firearmin the holster.

Coil 200 may include shield 240, around conductor 220 in FIG. 2 and tothe right and left sides in FIG. 3. Shield 240 shields conductor 220from electromagnetic noise and interaction with metal placed to the sideof coil 200 rather than the forward portion of coil 200. For example,shield 240 shields coil 200 from interaction with the metal of a vehicledoor when a user leans against the door while wearing a holster equippedwith detector 110. Shield 240 may also set (e.g., limit, focus, direct,point) the direction of the electromagnetic field generated by coil 200and thereby the direction of sensing by coil 200. In an implementation,shield 240 limits coil 200 to detecting metal forward (e.g., outwardwith respect to FIG. 2, and upward with respect to FIG. 3) of conductor220.

A shield may further extend to behind coil 200 (e.g., behind in FIG. 2,below in FIG. 3) (not shown) to provide shielding to a rear portion ofcoil 200.

A shield may be coupled to an electric potential (e.g., ground, anyvoltage). A shield may be uncoupled to an electric potential (e.g.,floating).

In an implementation, coil 200 includes conductor 220 formed on a firstlayer of PCB 210 and conductor 320 formed on a second layer of PCB 210.Conductors 220 and 320 are formed of metal (e.g., copper, aluminum,alloy). Conductor 220 is deposited on (e.g., in) layer 310 of PCB 210.Conductor 320 is deposited on (e.g., in) layer 330 of PCB 210. Conductor320 may include the same electrical (e.g., impedance, inductance) andphysical (e.g., number of turns, shape, position with respect to PCB 210and/or conductor 220) characteristics as conductor 220. Conductor 220may couple serially to conductor 320.

In the implementation of FIGS. 2 and 3, conductor 220 is positioned onfirst layer 310 of PCB 210. End portion 250 of conductor 220 extends toan edge of PCB 210 for electrical coupling. Conductor 320 is positionedon layer 330 of PCB 210. Conductor 320 has the same number of turns andshape as conductor 220. An end portion of conductor 220 couples to anend portion of conductor 320 via conductor 226 so that conductor 220serially couples to conductor 320. Because conductor 220 seriallycouples to conductor 320, a current flowing into end portion 250 ofconductor 220 flows out of end portion 350 of conductor 320. Applying avoltage between end portion 250 and end portion 350 applies a voltageacross conductor 220 and conductor 320.

In another implementation, coil 200 includes only conductor 220implemented on layer 310 of PCB 210.

Shield 240 may be integral with PCB 210. Shield 240 may be separate fromPCB 210. PCB 210 may be placed inside shield 240. Shield 240 may beplaced around all or a portion of PCB 210. A shield may be formed of ametal such as aluminum, nickel, or copper.

When coil 130 is excited (e.g., driven, powered) with a signal (e.g.,AC, impulse) from the sensor circuit 128, coil 130 generateselectromagnetic field 410 that extends from coil 130. Coil 130 may beposition proximate to wall 420 of a holster so that electromagneticfield 410 extends through wall 420 into the cavity of the holster wherethe firearm is positioned when the firearm is in the holster. In theabsence of the firearm, shown in FIG. 4, nothing interacts withelectromagnetic field 410. Sensor circuit 128 may measure the inductanceof coil 130 in the absence of the firearm from the holster.

When the firearm is inserted into the holster, referring to FIG. 5,metal from the firearm, in this case, barrel 510, interacts withelectromagnetic field 410 thereby changing the perceived (e.g.,measured) inductance of coil 130. Sensor circuit 128 can sense thedifference in the inductance when the firearm is present in the holster.In accordance with the difference, change, and/or magnitude of theinductance, sensor circuit 128 may deduce (e.g., detect, sense, measure)and report the presence of the firearm in the holster. Sensor circuit128 may further detect the magnitude of the inductance of the circuit,as discussed above, when the firearm is not present in the holster andreport the absence of the gun from the holster.

In another implementation, coil 130/200 may couple to a capacitor (notshown) to form an LC tank circuit. The signal provided by sensor circuit128 causes the LC tank circuit to resonate (e.g., oscillate). Sensorcircuit 128 may measure the frequency of resonation to determine whetherthe firearm is positioned in the holster. Sensor circuit 128 and/orprocessing circuit 112 may use the measured frequency of oscillation todetermine the inductance of coil 130/200.

The frequency of oscillation of the LC tank circuit is governed by theformula f=1/(2π*√(LC)). The value of the capacitance, C, is known andfixed, so the frequency of oscillation of the LC tank circuit isdetermined by the value of the inductance of coil 130. While firearm 142is absent from holster 150/650, the impedance of the LC tank circuit, L,is a first value L1. See FIG. 4. While the inductance of the LC tankcircuit is L1, the tank circuit oscillates at a first frequency f1.While firearm 142 is positioned in holster 150/650, see FIG. 5, themetal of firearm 142 interacts with the electromagnetic field from coil130/200 and thereby alters the value of the inductance of the LC tankcircuit. While firearm 142 is inserted in to holster 650 and proximateto coil 130/200 the inductance of the LC tank circuit is a second valueL2. While the inductance of the LC tank circuit is L2, the tank circuitoscillates at a second frequency f2.

Detector 110/610 may detect a difference (e.g., |f1−f2|, f1−f2, f2−f1)in frequency and/or a difference in parallel resistance of the LC tankcircuit to determine whether firearm 142 is present in holster 150/650.Or, detector 110/610 may use the measured frequency and/or resistance ofthe LC tank circuit (e.g., f1, f2) and the known value of thecapacitance of the LC tank circuit to determine the measured inductance(e.g., L1, L2) and whether firearm 142 is in or out of holster 150/650.

A firearm (e.g., gun) is a weapon that launches a projectile (e.g.,bullet, shell) to deliver a force of impact to an object via theprojectile. Conventional firearms include pistols (e.g., handguns) andrifles (e.g., long arms, shotguns, carbines) whether single shot,semiautomatic, or fully automatic. Many conventional firearms usecombustion of a pyrotechnic to launch the projectile.

Most conventional firearms are formed, at least partially, of metal.Most conventional firearms include at least a metal barrel. For example,firearm 642, shown in FIGS. 6-7 and 10, is a conventional firearm with ametal barrel. The metal of a firearm may interact with theelectromagnetic field generated by a coil. A sensor circuit may detectthe change in the electromagnetic field that results when the metal of afirearm is proximate to the coil that is generating an electromagneticfield.

A holster is a case (e.g., holder) that holds a firearm. Conventionalholsters for handguns have an opening to facilitate quick removal andinsertion of the handgun out of and into the holster respectively. Theshape of the holster generally conforms to the shape of the firearm(e.g., barrel, finger guard). A holster may be formed of any material.Common materials include leather and plastics. The material of manyholsters, such as those formed of leather or plastics, permit thepassage of an electromagnetic field through the walls of the holster sothat a sensor circuit may detect the presence or absence of a metalportion of a firearm inside the holster.

For example, holster 650 of firearm system 640, shown in FIGS. 6-7 and10, is suitable for accepting and holding firearm 642 and for mountingholster system 600 to a user's belt. Firearm system 640 includes holster650 and belt mount 670. Holster 650 includes mount 652 for mounting tobelt mount 670 to couple holster 650 to belt mount 670. As discussed infurther detail below, holster 650 may be decoupled from belt mount 670.Plate 660 and spacer 662 may be positioned between mount 652 and beltmount 670. Mount 652 may be coupled to plate 660 so that plate 660 andspacer 662 are positioned and retained between mount 652 and belt mount670.

In other implementations, belt mount 670 may be replaced with a thighmount, a MOLLE mount, and a quick-detach mount.

Mount 652 and belt mount 670 may have structures (e.g., holes) thatcorrespond to each other to facilitate mounting belt mount 670 to mount652 with retaining plate 660 and spacer 662 positioned in between.

While belt mount 670 is coupled to holster 650, holster 650 and beltmount 670 function as a single unit to hold firearm 642 and to mount toa user's belt. While mounted to the user's belt, firearm 642 may bewithdrawn and inserted into holster 650.

While plate 660 and spacer are mounted between mount 652 and belt mount670, holster 650, mount 652, plate 660, spacer 662, and belt mount 670function as a single unit to hold firearm 642 and to mount to a user'sbelt. Firearm 642 may be withdrawn and inserted into holster 650 whilethese components are coupled to each other. Plate 660 and/or spacer 662do not interfere with removing and/or inserting firearm 642 out of orinto holster 650.

Plate 660 includes positioner 612. Detector 610 may mount to positioner612. Positioner 612 positions and holds (e.g., maintains) detector 610proximate to holster 650, so that the electromagnetic field fromdetector 610 passes through the wall of holster 650 to determine, viameasuring inductance, impedance, and/or frequency, whether firearm 642is inserted into holster 650 or withdrawn from holster 650.

In another implementation, very high bond (“VHB”) mount 1010 positionsdetector 610 with respect to holster 650 so that the electromagneticfield from detector 610 passes through the wall of holster 650 todetermine, via measuring inductance, impedance, and/or frequency,whether firearm 642 is inserted into holster 650 or withdrawn fromholster 650.

VHB mount 1010 includes mount 1120 and VHB tape 1130. Detector 610mechanically mounts to mount 1120. Mount 1120 includes flexible tabs1124. Tabs 1124 may flex to conform to the exterior surface of holster650. Base 1126 is formed of a rigid material to maintain detector 610positioned with respect to mount 1120 and opening 1122. VHB tape 1130 isa very high bond tape that provides a strong adhering force betweenmount 1120 and holster 650. The shape of VHB tape 1130 is similar to theshape of mount 1120 including tabs 1124. VHB tape 1130 includes opening1132 that substantially aligns with opening 1122 when VHB tape 1130adheres to mount 1120 and holster 650. Opening 1122 and 1132 may reduceinterference with the electromagnetic field that issues from coil wall834 to detect the presence or absence of firearm 642 in holster 650.Opening 1122 and 1132 may further operate as a window to permit theserial number of detector 610 to be viewed prior to mounting.

After mount 1120 and VHB tape 1130 are coupled to holster 650, detector610 may be decoupled from mount 1120 to be service or replaced. Mount1120 and VHB tape 1130 remain coupled to the exterior of holster 650.With effort, mount 1120 and VHB tape may be decoupled from holster 650.

Processing circuit 112, memory 114, user interface 116, communicationcircuit 122, real-time clock 124, authentication circuit 126, sensorcircuit 128, coil 130, control 118, indicator 120, firearm system 140,and holster 150 may perform the functions and include the structures ofa processing circuit, a memory, a user interface, a communicationcircuit, a real-time clock, an authentication circuit, a sensor circuit,a coil, a control, an indicator, a firearm system, a firearm, and aholster respectively as discussed above.

In operation, processing circuit 112 controls, performs, or directs mostor all of the operations of detector 110. Processing circuit executes aprogram stored in memory 114 to perform or control the functions ofdetector 110. In an implementation, memory 114 is implemented as a flashmemory. Processing circuit 112 responsive to the program enters variousstates of operation (e.g., modes) to perform particular functions.Processing circuit 112 may perform method 1000 and/or 1100 in whole orpart as discussed below. In each mode, processing circuit 112 performsor controls the performance of specific operations. The modes and theoperations performed in the various modes are discussed below.

Processing circuit 112 receives information for a user via userinterface 116. In particular, as the user operates or controls control118, control 118 sends signals to processing circuit 112. Responsive tothe signals, processing circuit 112 performs functions, controls theperformance of a function, and/or changes from one mode to another mode.In an implementation, control 118 is a switch (e.g., electromechanical)that is manually operated by a user.

Processing circuit 112 also provides information to the user responsiveto the operation and/or modes of detector 110. Processing circuit 112provides signals to indicator 120 responsive to performance of anoperation, entering a state of operation, exiting a state of operation,and/or occurrence of a change in a state of operation. In animplementation, indicator 120 is an LED. Processing circuit 112 mayprovide a signal that turns the LED on and off to provide information tothe user. Processing circuit 112 may turn the LED on and off at afrequency of operation or in accordance with a pattern to provideinformation to the user and/or to indicate a state of operation ofdetector 110. A pattern and/or color of light provided by the LED mayindicate particular information to a user.

In another implementation, indicator 120 includes or exclusivelyprovides an audible sound or tactile feedback to provide the userinformation. Processing circuit 112 may control a sound producingindicator (e.g., buzzer) or tactile producing indicator (e.g., vibrator)in the same manner as the LED including providing sound or vibrations inaccordance with patterns.

Sensor circuit 128 cooperates with coil 130 to detect the presence orabsence of firearm 142 in holster 150. Sensor circuit 128 may drive coil130 with a signal (e.g., AC, DC, impulse), as discussed above, so thatcoil 130 generates an electromagnetic field. Sensor circuit 128 detects(e.g., senses, measures) the inductance, impedance, and/or frequency ofoscillation of the circuit that includes coil 130. When metal fromfirearm 142 is not proximate to coil 130, sensor circuit 128 detects afirst magnitude of inductance, impedance, and/or frequency. When metalfrom firearm 142 is proximate to coil 130, sensor circuit 128 detects asecond magnitude of inductance, impedance, and/or frequency. Sensorcircuit 128 may report the values (e.g., absolute, actual) of the firstmagnitude and the second magnitude and/or a change in the magnitude.

Processing circuit 112 may receive reports from sensor circuit 128.Processing circuit 112 may use the information that is detected bysensor circuit 128 to determine whether firearm 142 is in holster 150 orwhether holster 150 has been withdrawn from holster 150.

Responsive to determining that firearm 142 had been withdrawn fromholster 150, processing circuit 112 may instruct communication circuit122 to transmit a message. A message transmitted by communicationcircuit 122 may include information such as an identifier (e.g., serialnumber) of detector 110 and/or an identity of the user, as discussedabove. An identifier of detector 110 may be unique. The message mayfurther include the status of firearm 142 with respect to holster 150(e.g., withdrawn, inserted), a cryptographic signature, a time-stamp, astate of the battery (e.g., power level) of detector 110, the mode ofdetector 110 (e.g., test, calibrate, field, mute), the serial number offirearm 142, and/or the version of the software of detector 110. In animplementation, the message transmitted by communication circuit 122includes all or some of the above information.

The message transmitted by communication circuit 122 may be received byany electronic device capable of receiving messages that is incommunication with communication circuit 122. The message may betransmitted wirelessly. The electronic device receiving the message mayanalyze the information provided in the message. Responsive to thecontent of the information in the message, an electronic device mayperform an operation.

In an embodiment, body cameras, vehicle cameras, wireless microphonesand/or other recording systems may receive a message from detector 110.Responsive to determining that the message reports that a weapon hasbeen withdrawn from a holster, the recording system may (e.g.,permissive trigger) start capturing and/or recording information. Arecording system may use other information from a message to determinewhether or not to start recording. For example, if the information inthe message shows that detector 110 is in the mute mode (e.g., mute bitset to 1), discussed below, the recording system may decide to not startrecording. If the identifier of detector 110 or the user of detector 110does not match a list of permitted detectors or users, the recordingsystem may elect to not begin recording.

Communication circuit 122 may transmit a message upon detecting thatfirearm 142 has been placed into holster 150. A recording system mayelect (e.g., permissive trigger) to stop recording upon receiving suchinformation. A recording device may elect to continue recording eventhough firearm 142 has been returned to the holster so that the usermust manually terminate recording.

Communication circuit 122 may also receive information. For example,communication circuit 122 may receive data for updating the software ofdetector 110. Communication circuit 122 may receive information as tothe identity of the user of detector 110 (e.g., holster 150, firearm142). Communication circuit 122 may receive information as to the serialnumber of firearm 142.

Real-time clock 124 may provide time, day, and/or date information.Information from real-time clock 124 may be included in a messagetransmitted by communication circuit 122. Real-time clock 124 may alsoprovide time information for logging information as discussed above. Thepresent time of real-time clock 124 may be changed. Communicationcircuit 122 may receive a new time and the present time of real-timeclock 124 may be set to the new time. Setting real-time clock 124 to anew time may be performed during manufacture, to synchronize the timemaintained by two or more detectors 110, or to correct an error in thetime maintained by real-time clock 124. Real-time clock 124 may tracktime as universal time coordinated (“UTC”), yet report time in a localformat (e.g., UTC-7 for Arizona). Time reported by real-time clock 124may account for local time zone and/or daylight savings time. Real-timeclock 124 may also report time in UTC format and a receiving device maymake any adjustments to determine local time. Processing circuit 112 mayperform some or all of the functions of real-time clock 124.

The time maintained by real-time clock 124 may be updated in the fieldwhen detector 110 communicates with another system that includes a moreaccurate or more frequently updated clock. For example, the time ofreal-time clock 124 may be updated to match the time of a body-worncamera when detector 110 communicates with the body-worn camera. Inanother example, the time of real-time clock 124 may be updated to matchthe time of a handheld device (e.g., cell phone, smart phone) whendetector 110 communicates with the handheld device.

Processing circuit 112 may store information regarding the operation andstatus of detector 110. As discussed above, stored information may bereferred to as a log. Information that is logged may be stored in memory114. Log information may be retrieved. Communication circuit 122 maytransmit log information to another electronic device, such as a server.Log information may be used to analyze the performance and operation ofdetector 110. Log information may be used to detect faults in theoperation of detector 110. Information stored in a log may includeevents such as removal of firearm 142 from holster 150, insertion offirearm 142 into holster 150, activation of mute operation (e.g., mutemode), deactivation of mute operation, reset of detector 110, setting oftime of real-time clock 124, a change in configuration of detector 110,receiving and/or installing a software upgrade, reverting to an earlierversion of software, occurrence of a system fault either hardware orsoftware, transmission of a message by communication circuit 122,receipt of a message by communication circuit 122, battery energy level,report of battery energy level, battery change, magnitude of inductanceand/or impedance when firearm 142 is proximate, magnitude of inductanceand/or impedance when firearm 142 is not proximate, receipt of useridentity, successful authentication, unsuccessful authentication, stateof operation, and/or receipt of serial number of firearm 142.

Information stored in a log may be referred to as an entry. A singletype of information and/or information related to a single event oroccurrence may be stored in an entry. Each entry may include atime-stamp of when the entry was recorded. Real-time clock 124 mayprovide the time-stamp. The time-stamp may include time, day, and/ordate as discussed above.

Authentication circuit 126 may store keys used for encryption.Authentication circuit 126 may encrypt and/or decrypt data.Authentication circuit 126 may receive data from communication circuit122 for decrypting. Authentication circuit 126 may provide encrypteddata to communication circuit 122 for transmission. Authenticationcircuit 126 may cryptographically sign data prior to transmission.

Authentication circuit 126 may provide information for authenticating(e.g., confirming) the identity of detector 110. Authentication circuit126 may request information for authenticating the identity of anothersystem (e.g., server, recording system). A server may request thatdetector 110 authenticate its identity before the server communicateswith detector 110. For example, a server may request that detector 110authenticate its identity prior to providing detector 110 with sensitivedata, such as a software update. Detector 110 may request that a serverauthenticate its identity prior to providing log entries to the server.

In an implementation of detector 110, referring to FIGS. 6-11, detector610 includes front housing 810, screws 812, holes 960, circuitry 840,battery holder 820, battery 822, back housing 816, coil 830, shield 814,NFC tag 860, and shield 862. Front housing 810 may include userinterface 850. User interface 850 may include indicator 854 (e.g., LED)and control 852 (e.g., user-operated switch). Back housing 816 mayinclude coil cavity 832, and coil wall 834.

Circuitry 840 may include processing circuit 112, memory 114,communication circuit 122, real-time clock 124, authentication circuit126, and sensor circuit 128. Battery holder 820 holds battery 822.Battery 822 provides power to operate circuitry 840, coil 830, indicator854, and control 852. Screws 812 coupled front housing 810 to backhousing 816 to enclose circuitry 840, battery holder 820, battery 822,coil 830, shield 814, NFC tag 860, and shield 862.

Shield 814 is positioned around a perimeter of PCB 210 and thereforearound an edge of coil 830. Coil 830 is positioned in coil cavity 832 toposition coil 830 proximate to coil wall 834. Shield 814 remainspositioned around an edge of coil 830 while coil 830 is positioned incoil cavity 832. While detector 610 is in use with a holster, coil wall834 is position proximate to holster 650 so that the electromagneticwaves from coil 830 pass through the wall of holster 650 to detect thepresence or absence of metal. Detector 610 couples to positioner 612 toposition coil wall 834 proximate to holster 650.

Sensor circuit 128 and/or a processing circuit of sensor circuit 128, orprocessing circuit 112, may include a temperature sensor. Informationregarding temperature may be used to correct (e.g., adjust, compensatefor) operation of sensor circuit 128 or other components that varieswith temperature. For example, coil 200 may be formed on a PCB asdiscussed above. The electrical properties of coil 200 change overtemperature. Further, when sensor circuit 128 is implemented using anLDC, the LDC receives a clock from an oscillator. The oscillator may betemperature sensitive thereby affecting the operation and measurementsmade by the LDC. A coil and an oscillator used as a clock may becharacterized to determine how they vary over temperature. Processingcircuit 112 may use the current temperature and the characterizationdata to adjust operation to compensate for temperature.

Near-field-communication (“NFC”) tag 860 may communicate with a readervia wireless near-field communication. NFC tag 860 may be passive oractive. NFC tag 860 may provide information to a reader. In animplementation, NFC tag 860 provides the serial number of detector 610to the reader via NFC communication. NFC tag may operate independent ofprocessing circuit 112, memory 114, communication circuit 122, userinterface 116, sensor circuit 128, coil 130, real-time clock 124, andauthentication circuit 126. Any device (e.g., smartphone, tablet, mobilecomputer, recharging station) may perform the function of an NFC reader.Shield 862 may shield NFC tag 860 from the electrical andelectromagnetic noise produced by circuitry 840.

A user may operate control 852 to provide information to detector 610. Auser may operate control 852 by pressing the releasing control 852.Pressing control 852 may provide a signal to processing circuit 112 asdiscussed above. Detector 610 may provide information to a user viaindicator 854. Indicator 854 may provide information via illumination ofa light. Indicator 854 may operate to provide a pattern of on-offflashes (e.g., blinks) of light to convey information. The patternprovided by indicator 854 may depend on the operating state of detector610.

Processing circuit 112 may execute a program to perform the functions ofan operating state. As discussed above, an operating state may bereferred to as a mode of operation or simply a mode. In animplementation, the operating states of detector 110 and/or 610 mayinclude sleep 1020, test 1030, field 1040, mute 1050, calibrate 1060,reset 1070, rollback 1080.

Processing circuit 112 may cooperate with or received signals fromcontrol 120/852 to exit or enter a state of operation. Processingcircuit 112 may provide information to a user via indicator 120/854 uponentering or while operating in a state. Processing circuit 112 may use atimer or may measure an elapse of time using the time provided byreal-time clock 124 to enter and/or leave a state of operation.

In state diagram of method 1000 of FIG. 10, sleep 1020 is a low powerstate in which most of the circuits of detector 160/610 are powered downto save battery power. In an implementation, the only circuitry that isactive is the portion of processing circuit 112 that monitors control118 to detect when control 118 has been pressed. Operation transitionsinto sleep 1020 from test 1030 after the expiration of a period of time.In an implementation, the period of time is 30 seconds. Operation movesfrom sleep 1020 to test 1030 responsive to activation of control 118. Inan implementation, indicator 120/854 (e.g., LED) blinks three times witha green light to confirm the transition from sleep 1020 to test 1030.

In test 1030, the circuits of detector 160/610 are powered up so that auser may verify the proper operation of detector 160/610. In test 1030,a user may verify that detector 160/610 detects the insertion of firearm142 into holster 150/650 and removal of firearm 142 from holster150/650. When firearm 142 is inserted into holster 150/650, indicator120/854 (e.g., LED) provides light that is visible to the user. Whenfirearm 142 is removed from holster 150/650, indicator 120/854 ceases toprovide light.

As stated above, operation stays in test 1030 for a duration of timebefore returning to sleep 1020. In an implementation, operation movesfrom test 1030 to sleep 1020 after a 30 second period of time. Thirtyseconds is enough time for a user to insert and remove firearm 142 fromholster 150/650 several times. If indicator 120 indicates properdetection of insertion and removal, a user may press control 118 to moveoperation from test 1030 to field 1040. In an implementation, control118 must be pressed with a long press of 5 seconds or greater foroperation to move from test 1030 to field 1040.

While in test 1030, if indicator 120/854 shows that detector 160/610 isnot properly detecting the insertion and removal of firearm 142, a usermay elect to calibrate detector 160/610. While in test 1030, a user maymove into calibrate 1060 by pressing control 118 with a double press. Inan implementation, a double press is one press on control 118, a pause,then a second press on control 118. The length of the pause may have anupper boundary.

In calibrate 1060, detector 110/610 determines the magnitude of theinductance or impedance that indicates that the weapon is in and/or outof the holster. In one implementation, detector 110/610 performs severalreadings of the inductance and/or impedance while the firearm 142 iswithdrawn from holster 150/650. Detector 110/610 averages the value ofthe measured inductance and/or impedance to determine a base-line valueof inductance and/or impedance. The base-line value is subtracted fromreadings performed in field 1040. A change from the base-line value,either more or less, indicates that firearm 142 is in holster 150/650.

In another implementation, detector 110/610 performs several readingswhile firearm 142 is in holster 150/650 and averages the values tocreate a base-line value for when firearm 142 is in holster 150/650.Detector 110/610 also performs several readings while firearm 142 is outof holster 150/650 and averages the values to create a base-line valuefor when firearm 142 is out of holster 150/650. While in the operatingstate field 1040, detector 110/610 uses the base-line values for firearm142 being in and out of holster 150/650 to determine when firearm 142 isin or out of holster 150/650.

In an implementation, indicator 120/854 blinks three times with a greenlight after the double press on control 118 to confirm that operationhas moved from test 1030 to calibrate 1060. Once calibration iscomplete, indicator 120/854 blinks three times with a green light toshow the transition from calibrate 1060 back to test 1030.

While in operating state test 1030, a user may use control 118 to movefrom operating state test 1030 to operating state field 1040. A user maypress control 118 with a long-press to initiate the change from test1030 to field 1040. In an implementation, a long press is a press thatis greater than 5 seconds, but less than 25 seconds. In animplementation, indicator 120/854 blinks 3 times with a green light toindicate the transition from test 1030 to field 1040.

In the operating state field 1040, detector 110/610 performs method 1100to monitor the presence or absence of firearm 142 in holster 150/650.Method 1100 includes operating states wait 1102, activate 1104, measure1106, present 1108, transmit 1110, and count 1112.

In wait 1102, detector 110/610 waits for a period of time. While in wait1102, the circuits of detector 110/610 are in a low power state to saveenergy to prolong the life of the battery. At the end of the period oftime, detector 110/610 transitions to operating state activate 1104.

In activate 1104, detector 110/610 activates the coil and measuresinductance, impedance and/or frequency of oscillation to detect thepresence or absence of firearm 142 in holster 150/650.

In another implementation, the Texas Instruments inductance-to-digitalintegrated circuit LCD1101 controls the operation of coil 130/200,measures the frequency, inductance, and/or impedance, and reports adigital value to processing circuit 112.

After activate 1104 has activated coil 130/200 and returns a value ofthe frequency of the LC tank circuit, the inductance of coil 130/200,and the impedance of coil 130/200 and/or LC tank circuit, operationmoves to present 1108.

In operating state present 1108, detector 110/610 uses the informationdetermined in activate 1104 to determine whether firearm 142 is presentin holster 150/650 or whether firearm 142 is absent from holster150/650. In an implementation, processing circuit 112 compares the valueprovided by the LDC1101 integrated circuit or the value of the measuredfrequency of the LC tank circuit, or the measured value of theinductance of the LC tank circuit to one or more base-line values todetermine whether firearm 142 is in or out of holster 150/650. Iffirearm 142 is present in holster 150/650, execution of method 1100moves to operating state wait 1102. If firearm 142 is not present inholster 150/650, execution moves to transmit 1110.

In transmit 1110, detector 110/610 transmits a message that containssome or all of the information discussed above including that firearm142/642 has been removed from holster 150/650. Any recording system thatreceives the message may determine that the information provided by themessage indicates that firearm 142/642 has been removed from holster150/650. A recording system may (e.g., permissive trigger) start tocapture and/or record information responsive to such information in themessage. After transmitting the message, execution moves to operatingstate count 1112.

In operating state count 1112, detector 110/610 determines whether themessage has been transmitted a certain number of times. In animplementation, the message is transmitted once per second for 30seconds. If the message has been transmitted the predetermined number oftimes, execution moves to operating state wait 1102. If the message hasnot been transmitted the predetermined number of times, executionreturns to operating state transmit 1110.

During the time that detector 110/610 remains in field 1040, indicator120/854 may be shut off to conserve energy and to not blink when darkthereby disclosing the position of the user.

In the event that a user wishes to remove firearm 142 from holster150/650 without requesting that any cameras or other recording devicesstart recording, the user may put detector 110/610 in the mute 1050operating state. For example, an officer may need to remove firearm 142from holster 150/650 temporarily upon entering a court house. A user mayrequest a transition from field 1040 to mute 1050 by pressing control120/852 with a long press.

Detector 110/610 remains in the mute mode for a period of time (e.g., 30seconds). At the expiration of the period of time, operation returns tofield 1040. While in mute 1050, detector 110/610 performs method 1100;however, irrespective of whether firearm 142 is in or out of holster150/650, the transmitted messages include a mute bit whose value is setto a one. Setting the mute bit to a one indicates that the user asrequested the mute mode and the state of operation is presently in mute1050. Cameras or other recording devices ignore messages that include amute bit with the value set to a one. Operation remains in mute 1050 forthe predetermined amount of time, thereby possibly repeatedly executingmethod 1100 several times.

While in mute 1050, indicator 120/854 blinks to indicate that operationis in mute 1050. However, additional information may be provided byindicator 120/854 while in mute 1050. For example, indicator 120/854blinks with a red color if the battery is low and with a green color ifthe battery level is not low (e.g., above a pre-determined level).

At any time and from any state of operation, a user may press control120/852 for an extended long press (e.g., 25 seconds) to transition fromwhatever the present state of operation is (e.g., sleep 1020, test 1030,calibrate 1060, field 1040, mute 1050) to reset 1070 operating set.Indicator 120/854 confirms the transition to reset 1070 by blinking witha blue color.

While in reset 1070, detector 110/610 performs operations to reset allcomponents of indicator 120/854 to a known state. After setting allcomponents to a known state, detector 110/610 restarts operation andenters operating state test 1030.

At any time and from any state of operation, a user may press control120/852 for an even longer extended long press (e.g., 40 seconds) totransition from whatever the present state of operation is to rollback1080 operating set. Indicator 120/854 confirms the transition torollback 1080 by alternately blinking with a blue and green color.

While in rollback 1080, detector 110/610 selects for execution aprevious version of software. Processing circuit 112 executes a storedprogram (e.g., software, firmware) stored in memory 114 to perform thefunctions of detector 110/610. The stored program may be updated byreceiving new software via wired or wireless communication. Detector110/610 may wirelessly communicate with a hand-held device (e.g.,smartphone, tablet) or a server to receive updated software. Detector110/610 may store two or more version of software including the factoryversion loaded into detector 110/610 at manufacture. In the event thatthe present version of software does not operate properly (e.g., bug,corruption of memory 114), a user may activate operating state rollback1080 to return to a prior version of the software.

Once the prior version of the software has been selected as the presentversion of software, operation moves to reset 1070 to reset operationexecuting the different version of software.

In an implementation, field 1040 may perform a further method, inaddition to method 1100, to periodically transmit a status message thatis different and separate from the message transmitted in transmit 1110.A status message may include information regarding the status ofdetector 110/610. A status message may exclude information regarding thestatus of firearm 142/642 (e.g., withdrawn, inserted). In animplementation, the status message is transmitted every 40 seconds. Thestatus message includes information regarding the status of the battery(e.g., charge level).

Other implementations include the implementations provided below.

A system for positioning a detector to detect removal of a providedfirearm from a provided holster, the holster includes a mount and a beltmount, the mount coupled to the holster, the mount configured to coupleto the belt mount, the system comprising: a plate; the detector; and apositioner, the positioner configured to couple to the detector and tothe plate; wherein the plate is configured to be positioned between themount and the belt mount prior to coupling the mount to the belt mount;coupling the mount to the belt mount retains the plate between theholster and the belt mount; coupling the positioner to the detector andto the plate while the plate is retained between the mount and the beltmount positions the detector proximate to a wall of the holster; andwhile the detector is proximate to the wall of the holster, anelectromagnetic field of the detector passes through the wall to detectremoval of the firearm from the holster.

The foregoing description discusses preferred embodiments of the presentinvention, which may be changed or modified without departing from thescope of the present invention as defined in the claims. Examples listedin parentheses may be used in the alternative or in any practicalcombination. As used in the specification and claims, the words‘comprising’, ‘comprises’, ‘including’, ‘includes’, ‘having’, and ‘has’introduce an open-ended statement of component structures and/orfunctions. In the specification and claims, the words ‘a’ and ‘an’ areused as indefinite articles meaning ‘one or more’. While for the sake ofclarity of description, several specific embodiments of the inventionhave been described, the scope of the invention is intended to bemeasured by the claims as set forth below. In the claims, the term“provided” is used to definitively identify an object that not a claimedelement of the invention but an object that performs the function of aworkpiece that cooperates with the claimed invention. For example, inthe claim “an apparatus for aiming a provided barrel, the apparatuscomprising: a housing, the barrel positioned in the housing”, the barrelis not a claimed element of the apparatus, but an object that cooperateswith the “housing” of the “apparatus” by being positioned in the“housing”. The invention includes any practical combination of thestructures and methods disclosed. While for the sake of clarity ofdescription several specifics embodiments of the invention have beendescribed, the scope of the invention is intended to be measured by theclaims as set forth below.

The words “herein”, “hereunder”, “above”, “below”, and other word thatrefer to a location, whether specific or general, in the specificationshall refer to any location in the specification.

What is claimed is:
 1. A system for detecting a presence of a weapon ina holster and an absence of the weapon from the holster, the systemcomprising: a mount comprising a tape, wherein the tape provides anadhering force between the mount and the holster; a detector thatcouples to the mount, the detector comprising a sensor circuit, a coil,a first communication circuit, a memory, and a processing circuitcommunicatively coupled to the sensor circuit, the first communicationcircuit, and the memory, wherein the sensor circuit cooperates with thecoil to detect the presence of the weapon in the holster and the absenceof the weapon from the holster, and wherein the processing circuit isconfigured to perform first operations comprising: determining thepresence of the weapon in the holster using a value of a first magnitudedetected by the sensor circuit when metal from the weapon is proximatethe coil; determining the absence of the weapon from the holster using avalue of a second magnitude detected by the sensor circuit when themetal from the weapon is not proximate the coil; while in a field mode,and responsive to determining the absence of the weapon from the holsterusing the value of the second magnitude detected by the sensor circuit,transmitting a first message via the first communication circuit; whilein a test mode, and responsive to determining the presence of the weaponin the holster using the value of the first magnitude detected by thesensor circuit, transmitting first information via the firstcommunication circuit; while in the test mode, and responsive todetermining the absence of the weapon from the holster using the valueof the second magnitude detected by the sensor circuit, transmittingsecond information via the first communication circuit; and responsiveto receiving third information via the first communication circuit,entering a calibrate mode; and a smart phone comprising a secondcommunication circuit and a touch screen, wherein: a user interface forthe detector is implemented by the smart phone; the user interfacecomprises an indicator and a control; responsive to receiving the firstinformation via the second communication circuit, the presence of theweapon is indicted via the indicator; responsive to receiving the secondinformation via the second communication circuit, the absence of theweapon is indicated via the indicator; responsive to a first operationof the control, the third information is communicated to the detectorvia the second communication circuit; and the control includes a portionof the touch screen.
 2. The system of claim 1, wherein the tapecomprises a very high bond tape and the mount comprises a very high bondmount.
 3. The system of claim 1, wherein the user interface comprises asecond control and, responsive to a second operation of the secondcontrol, components of the indicator are reset to a known state and thetest mode is entered.
 4. The system of claim 1, wherein: the firstmagnitude comprises a first magnitude of inductance, impedance, and/orfrequency; and the second magnitude comprises a second magnitude ofinductance, impedance, and/or frequency.
 5. The system of claim 1,wherein the operations further comprise, while in the field mode andresponsive to determining the presence of the weapon in the holsterusing the value of the first magnitude, transmitting a second messagevia the first communication circuit.
 6. The system of claim 5, furthercomprise a recording device configured to receive the second messageand, upon receiving the second message, continue recording.
 7. Thesystem of claim 1, further comprising a body-worn camera configured toreceive the first message and initiate recording responsive to the firstmessage.
 8. The system of claim 7, wherein: the first message includes aunique identifier for the detector; and the recording is initiatedresponsive to the unique identifier matching a list of permitteddetectors.
 9. The system of claim 1, wherein the operations comprise:while the calibration mode, determining a third magnitude of impedanceor inductance detected by the sensor circuit that indicates the presenceof the weapon in the holster and/or the absence of the weapon from theholster.
 10. The system of claim 9, wherein the operations furthercomprise: while in the calibrate mode, performing several readings ofthe third magnitude of impedance or inductance detected by the sensorcircuit.
 11. The system of claim 10, wherein the operations furthercomprise: while in the calibrate mode, averaging the several readings tocreate a base-line value.
 12. The system of claim 11, whereindetermining the presence of the weapon in the holster using the value ofthe first magnitude detected by the sensor circuit comprises: comparingthe value of the first magnitude to the base-line value to determine thevalue of the first magnitude indicates the weapon is inserted in theholster.
 13. The system of claim 11, wherein determining the absence ofthe weapon from the holster using the value of the second magnitudedetected by the sensor circuit comprises: comparing the value of thesecond magnitude to the base-line value to determine the value of thesecond magnitude indicates the weapon is withdrawn from the holster. 14.A method for detecting a presence of a weapon in a holster and anabsence of the weapon from the holster, the method comprising: coupling,via a mount comprise a tape, a detector to the holster; detecting, by asensor circuit of the detector, a value of a first magnitude when metalfrom the weapon is proximate a coil of the detector; detecting, by thesensor circuit, a value of a second magnitude when the metal from theweapon is not proximate the coil of the detector; determining, by aprocessing circuit of the detector, the presence of the weapon in theholster using the value of the first magnitude detected by the sensorcircuit; determining, by the processing circuit, the absence of theweapon from the holster using the value of the second magnitude detectedby the sensor circuit; while in a field mode of the detector, andresponsive to determining the absence of the weapon from the holster,wirelessly transmitting a first message via a first communicationcircuit of the detector; while in a test mode of the detector, andresponsive to determining the presence of the weapon in the holster,transmitting first information via the first communication circuit;while in the test mode, and responsive to determining the absence of theweapon from the holster, transmitting second information via the firstcommunication circuit; responsive to receiving third information via thefirst communication circuit, entering, by the processing circuit, acalibrate mode; responsive to receiving the first information via asecond communication circuit of a smart phone, indicating, via anindicator of a user interface of the smart phone, the presence of theweapon in the holster, wherein the indicator comprises a touch screen ofthe smart phone; responsive to receiving the second information via thesecond communication circuit, indicating, via the indicator, the absenceof the weapon from the holster; and responsive to a first operation of afirst control of the user interface, communicating the third informationto the detector via the second communication circuit, wherein thecontrol comprises a portion of the touch screen.
 15. The method of claim14, wherein the user interface comprises a second control and theoperations further comprise, responsive to a second operation of thesecond control, resetting components of the indicator to a known state.16. The method of claim 14, wherein: the first magnitude comprises afirst magnitude of inductance, impedance, and/or frequency; and thesecond magnitude comprises a second magnitude of inductance, impedance,and/or frequency.
 17. The method of claim 14, wherein the operationscomprise: while the calibration mode, determining, by the processingcircuit, a third magnitude of impedance or inductance detected by thesensor circuit that indicates the presence of the weapon in the holsterand/or the absence of the weapon from the holster.
 18. The method ofclaim 17, wherein the operations further comprise: while in thecalibrate mode, performing, by the processing circuit, several readingsof the third magnitude via the sensor circuit.
 19. The method of claim14, wherein: indicating the presence of the weapon in the holstercomprises providing, via the indicator, light that is visible to a user;and indicating the absence of the weapon from the holster comprisesceasing, via the indicator, providing the light.
 20. A system fordetecting a presence of a weapon in a holster and an absence of theweapon from the holster, the system comprising: a detector comprising asensor circuit, a coil, a communication circuit, a memory, and aprocessing circuit communicatively coupled to the sensor circuit, thecommunication circuit, and the memory, wherein the sensor circuitcooperates with the coil to detect the presence of the weapon in theholster and the absence of the weapon from the holster, and wherein theprocessing circuit is configured to perform operations comprising:determining the presence of the weapon in the holster using a value of afirst magnitude detected by the sensor circuit when metal from theweapon is proximate the coil; determining the absence of the weapon fromthe holster using a value of a second magnitude detected by the sensorcircuit when the metal from the weapon is not proximate the coil; whilein a field mode, and responsive to determining the absence of the weaponfrom the holster, wirelessly transmitting a trigger via thecommunication circuit; while in a test mode, and responsive todetermining the presence of the weapon in the holster, communicatingfirst information via the communication circuit; while in the test mode,and responsive to determining the absence of the weapon from theholster, communicating second information via the communication circuit;and responsive to receiving third information via the communicationcircuit, entering a calibrate mode; a mount comprising a very high bondtape, wherein the very high bond tape adheres the mount to the holsterand the mount positions the detector with respect to the holster; and auser interface for the detector, wherein: the user interface isimplemented by an electronic device that includes a touch screen;responsive to the first information being received by a secondcommunication circuit of the electronic device, the user interfaceprovides the first information visually via the touch screen to indicatethe presence of the weapon in the holster; responsive to the secondinformation being received by the second communication circuit, the userinterface provides the second information visually via the touch screento indicate the absence of the weapon from the holster; and responsiveto operation of a control of the user interface, the third informationis communicated to the detector, wherein the operation occurs by aselection of a portion of the touch screen.